Safety detent mechanism for fuses of explosive projectiles

ABSTRACT

A safety device which minimizes the hazard in handling an explosive fused projectile. The fuse rotor is locked by one or more detents and if unlocked would be rotated so as to arm the fuse. Upon firing of the projectile, the detents respond to the combination of setback forces and centrifugal forces for unlocking the rotor.

I United States Patent 1 1111 3,807,308 Malatesta Apr. 30, 1974 SAFETY DETENT MECHANISM FOR FUSES 2,044,026 6/1936 Zomig 102/80 0 EXPLOSIVE PROJECTILES 3,022,733 2/1962 Junghans et a1. 102/79 X 3,416,894 l2/l968 Brooks et al 102/78 Inventor: Edward Malfltesw, Phlladelphla. 1,973,738 9/1934 Zomig 102/80 [73] Assignee: The United States of America as Primary ExaminerSamuel W. Engle represented by the Secretary of the Attorney, Agent, or FirmEdward J. Kelly; Herbert Army, Washington, DC. Berl; Samuel Kane [22] Filed: June 27, 1972 21 Appl. No.: 266,801 [57] ABSTRACT A safety device which minimizes the hazard in han- 52 us. (:1. 102/78 102/79 dung expbsive fused The fuse is 51 Int. Cl. F42; 15/24 locked by more detents and if wuld [58] Field of Search 102/80 79 78 76 be rotated as arm the fuse- P firing 0f the projectile, the detents respond to the combination of [56] References Cited setback forces and centrifugal forces for unlocking the UNITED STATES PATENTS 3,045,598 7/1962 Brown et al. 102/80 4 Claims, 5 Drawing Figures b I I 5 36 522 20 5436 38 1 SAFETY DETENT lVlECI-IANISM FOR FUSES OF EXPLOSIVE PROJECTILES STATEMENT OF GOVERNMENT INTEREST BACKGROUND OF THE INVENTION The present method of solving the problem of safe handling of explosive projectiles consists in using two completely separate systems, one of which is activated by setback forces and the other by centrifugal forces, the latter forces commonly known in the art as spin forces. It is necessary for the spin forces to act at the precise moment that setback forces occur. At that time, the fuse setback pin is disengaged from the fuse rotor and the spin forces should move the rotor; however, due to the tremendous setback forces on the rotor, the rotor sometimes fails to unlock and remains locked until the setback forces subside. When the setback forces subside, the setback pin returns and reengages with the rotor, locking the rotor in place. Since setback force and spin force vary considerably from application to application, it is almost impossible to design a setback pin that will operate for every application.

Most recently, the setback pin has been eliminated from the rotor, and the fuse mechanism so modified that the fuse is locked by a setback device on the fuse timing disc. With this construction, it is possible that one safety device will function when the fuse is dropped in such a direction that setback forces are simulated. The fuse will now arm on spin forces only. Fuses in this state have proved to be extremely dangerous.

SUMMARY OF THE INVENTION The principal object of the present invention is to provide a fuse mechanism which permits the safe handling of explosive projectiles.

Another object of the invention is to provide a single safety device for the fuse mechanism of an explosive projectile which can respond to both setback and centrifugal forces.

A further object of the invention is to provide a fuse mechanism for explosive projectiles which will arm only upon the coaction of setback forces and centrifugal forces.

In accordance with the above objects and considered first in one of its broader aspects, a safety detent mechanism for the fuse of an explosive projectile which is constructed to be fired through a helically rifled gun so as to acquire a spinning motion and be subjected to centrifugal forces, and which is further subjected to setback forces upon being fired from the gun in accordance with the invention may comprise a body fixed to the projectile, a rotor rotatably mounted on the projectile for arming the fuse when permitted to rotate, and a detent removably locking the rotor to the body and against rotation relative to the body, the detent being responsive to the combination only of the setback forces and centrifugal forces for releasing the rotor from the body.

The invention will be more clearly understood when the following detailed description of the preferred embodiment thereof is read in conjunction with the accompanying drawing which is set forth below.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a plan view, with part broken away, of a safety detent mechanism constructed in accordance with the invention.

FIG. 2 is a sectional view taken on line 22 of FIG. 1.

FIGS. 3 and 4 are similar to FIG. 2 and show successive positions of a rotor locking mechanism.

FIG. 5 is an enlarged side view of a fragment of the apparatus of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 of the drawing, the invention comprises a housing or fuse body 10 secured to an explosive projectile, not shown, and provided with a central counterbore 12 in which is rotatably positioned a rotor 14 which is secured axially in the body 10 by means of a cover plate 16 secured to the body 10 in any suitable manner as by means of screws 18 which pass through openings in the cover plate 16 to threadedly engage in tapped holes in the body 10. The body 10 and the cover plate 16 are provided with coaxial bearings 20 and 22, respectively, in which are journaled for rotation, short end shaft portions 24 and 26 of the rotor 14.

One or more detent assemblies 28 and 30, of which there are two in the present embodiment of the invention, are each mounted in one of radial slots 32 and 34 in the body 10-; however, the slots 32 and 34 need not be exactly radial, if desired. The detent assemblies 28 and 30 are similar in construction and operation so a description will be given of only one of them.

The detent assembly 30, for example, comprises a detent 36 (FIG. 2) in which is press-fitted or otherwise secured a pivot pin 38 which is freely inserted into opposing slots 40 and 42 (FIG. 1) in the body 10 so as to come to rest against the inner ends of the slots 40 and 42, respectively. A pin 44 (FIGS. 2 and 5) is pressfitted in or otherwise secured to the detent 36 and is provided with a slot 46 for loosely receiving one end of a torsion spring 48 which is wound around the pivot pin 38, the other end of which bears against a surface 50 of the body 10 at the leftward end of the slot 32.

The detents 36 and 36 are freely positioned in diametrically opposite slots 52 and 54 of the rotor 14 so as to lock the rotor 14 against rotation relative to the body 10, and with their respective centers of gravity 56 and 58 positioned forward of the axes of the pivot pins 38 and 38' (FIG. 2) in the direction of firing, and with the torsion springs 48 and 48' formed so as to locate the detents in this position.

In the present embodiment of the invention, the rotational axis of the rotor 14 is coaxial with the longitudinal or firing axis 64 of the associated explosive projectile; however, this coaxial relation of the rotor 14 to the projectile is preferable, but not limiting.

When the associated explosive projectile is fired through a helically rifled gun (upwardly, as viewed in FIG. 2), it is subjected first to setback forces and then to centrifugal forces. As the setback forces occur in the direction indicated by the arrows 60 and 62 (FIG. 3), parallel to the firing axis 64 of the projectile, the detents 36 and 36 rotate with their respective pivot pins 38 and 38 about the axes of the pivot pins 38 and 38 so that their centers of gravity 56 and 58 assume a position rearward of the pivot pins 38 and 38', as shown in FIG. 3. In this position, the detents 36 and 36' are still in locking engagement in the rotor grooves 52 and 54. As the centrifugal or spin forces develop, as indicated by arrows 65 (FIG. 4), the detents 36 and 36 rotate further about the axes of their respective pivot pins 38 and 38 until their centers of gravity 56 and 58 move in a generally radial direction outwardly from the firing axis 64 until the detents 36 and 36' move out of engagement with the rotor slots 52 and 54, thereby freeing the rotor 14 for rotation. When this occurs, the rotor 14 will be rotated by fuse mechanism, not shown, until the fuse detonator 66 (FIG. 1), which is pressfitted in or otherwise secured to the rotor 14, comes into line with the fuse firing pin, not shown, thereby arming the fuse.

It will now be seen, as indicated earlier, that the detents 36 and 36 will only respond to the combination of setback forces and centrifugal forces for unlocking the rotor 14. It may also now be perceived from an inspection of FIG. 2 that, in the event centrifugal forces should occur prior to or in the absence of setback forces, the detents 36 and 36 will move or press against the respective stop surfaces 50 and 50' and remain lockingly engaged in the rotor grooves 52 and 54.

I claim:

1. A safety detent mechanism for the fuse of an explosive projectile which is constructed to be fired through a helically rifled gun so as to acquire a spinning motion and be subjected to centrifugal forces, and which is further subjected to setback forces upon being fired from said gun comprising a body fixed to said projectile,

a rotor rotatably mounted on the projectile for arming the fuse when permitted to rotate and having its axis of rotation parallel to the firing axis of said projectile, said rotor having a locking groove,

a detent pivotally mounted to the body and removably inserted in said groove in a locking position for locking the rotor to the body and against rotation relative to the body, said detent being mounted for movement on a fixed pivotal axis relative to said body which is normal to said rotor axis and to a plane containing the firing axis of said projectile, and

resilient means yieldably biasing said detent into said locking position,

said detent having its center of gravity forward of said pivotal axis in the direction of said firing axis in the pre-fired condition of the projectile and being responsive to the combination only of said setback forces and said centrifugal forces for moving on its pivotal axis out of said groove against the biasing action of said resilient means for releasing the rotor from the body.

2. A detent mechanism according to claim 1 wherein upon the occurrence of setback forces only the center of gravity of the detent moves rearwardly of said pivotal axis in the direction of said firing axis and the detent remains lockingly engaged in said groove.

3. A detent mechanism according to claim 2 wherein upon the occurrence of said centrifugal forces following the occurrence of said setback forces the detent moves out of engagement with said groove.

4. A detent mechanism according to claim 3 characterized further in that said body is provided with a stop surface, and wherein in the event centrifugal forces should occur prior to or in the absence of setback forces the detent will move against said stop surface and remain lockingly engaged in said groove. 

1. A safety detent mechanism for the fuse of an explosive projectile which is constructed to be fired through a helically rifled gun so as to acquire a spinning motion and be subjected to centrifugal forces, and which is further subjected to setback forces upon being fired from said gun comprising a body fixed to said projectile, a rotor rotatably mounted on the projectile for arming the fuse when permitted to rotate and having its axis of rotation parallel to the firing axis of said projectile, said rotor having a locking groove, a detent pivotally mounted to the body and removably inserted in said groove in a locking position for locking the rotor to the body and against rotation relative to the body, said detent being mounted for movement on a fixed pivotal axis relative to said body which is normal to said rotor axis and to a plane containing the firing axis of said projectile, and resilient means yieldably biasing said detent into said locking position, said detent having its center of gravity forward of said pivotal axis in the direction of said firing axis in the pre-fired condition of the projectile and being responsive to the combination only of said setback forces and said centrifugal forces for moving on its pivotal axis out of said groove against the biasing action of said resilient means for releasing the rotor from the body.
 2. A detent mechanism according to claim 1 wherein upon the occurrence of setback forces only the center of gravity of the detent moves rearwardly of said pivotal axis in the direction of said firing axis and the detent remains lockingly engaged in said groove.
 3. A detent mechanism according to claim 2 wherein upon the occurrence of said centrifugal forces following the occurrence of said setback forces the detent moves out of engagement with said groove.
 4. A detent mechanism according to claim 3 characterized further in that said body is provided with a stop surface, and wherein in the event centrifugal forces should occur prior to or in the absence of setback forces the detent will move against said stop surface and remain lockingly engaged in said groove. 